This invention relates to saw apparatus, and more particularly, to saw apparatus which is known in the industry as a gang or rip saw, and which normally includes plural circular saws adjustably mounted on a power-driven saw arbor so as to be relatively shiftable laterally of each other to change the width of boards cut by the machine.
Saw apparatus of this description is illustrated in prior U.S. Pat. Nos. 4,414,875 and 3,202,189. In these patents, and as typifies the usual rip saw, plural saws are disposed side-by-side on a power-driven saw arbor, with the saws keyed to the arbor so that rotation of the arbor produces rotation of the saws. Saw shifters are provided which are actuated to shift the position of respective saws along the saw arbor. Ordinarily, the arbor extends horizontally in the saw apparatus, and a suitable conveyor system transports lumber or work-pieces in a direction extending transversely of the saw arbor and in a path which extends adjacent the peripheries of the various saws.
In saw apparatus of the above description, difficulties have been experienced in properly supporting and holding down the lumber as it moves in the vicinity of the saws and while being cut. This is particularly true in connection with the holding down and supporting of the end of a piece of lumber during its cutting. Further explaining, a board on traveling through a saw normally is held down in regions on opposite sides of where the cut is being made. As the trailing end of the board travels into a position to be cut, the board moves into a position where it is held down on the downstream side of the saw arbor only, and the extreme upstream end of the board has moved free of any hold-down means. When this occurs, the action of the saw causes the board to flutter, resulting in tear-out of wood material where the cut is being made and the production of a ragged cut. Obviously this is detrimental in equipment designed to produce precision cutting with minimum wastage of wood.
The problem of proper holding down boards as they are being cut is complicated by several factors, which include the fact that saw apparatus normally must handle material of various thicknesses, and with thinner material any flutter in a board end becomes more pronounced. Further, any gang saw mechanism includes some system for adjustably positioning the respective saws, so that any hold-down system provided must not interfere with movement of the saws or operation of the shifter mechanism producing their movement.
Generally, an object of the invention is to provide saw apparatus, such as a rip saw, which includes one or more saws shiftable along an arbor, with improved means for clamping or holding down work-pieces during their cutting.
Another object is to provide such saw mechanism where the hold-down or clamp means is adjustable, to take care of variations in thickness in the work-pieces handled.
Yet another further object is to provide a novel clamp or hold-down means in a gang or rip saw which includes shoe structure extending parallel to the arbor on one side where the cutting is performed, and a novel mounting for the shoe structure whereby it provides the support desired for thick and thin pieces.
In a preferred embodiment of the invention, the shoe structure and a hold-down roll are both part of a moveable assembly located on the feed side where cutting occurs. The shoe structure and hold-down roll move along an inclined path down and toward support for work-pieces, thus properly engaging work-pieces of various thickness. The structure guiding the shoe and hold-down roll is relatively compact and out of the way of the working region of the machine.